This invention relates to tubes which are useful as medical devices in a number of medical applications, including nerve re-generation, and to the production of such tubes.
Because mature neurons do not replicate, nerve injuries present a challenge for successful rehabilitation. However, under the right conditions, axon extensions of peripheral nerves can regenerate over gaps caused by injury, reconnecting with the distal stump and eventually re-establishing nerve function. Current treatments for an injury-induced break in a nerve typically rely on donor tissue obtained from a second operative site of the patient. The donor tissue may be an autologous nerve graft, vein graft or arterial graft which is sutured to the two ends of the severed nerve. However, these treatments raise the possibility of function loss at the donor site, formation of potential painful neuromas, and structural differences between donor and recipient grafts, not to mention a potential shortage of graft material where extensive repairs are required. A promising alternative for nerve regeneration which avoids the above problems is an artificial graft.
The artificial graft is a synthetic tube that bridges the gap between the nerve stumps and directs and supports nerve regeneration. The tube, which is known as a nerve guide conduit, or NGC, may be implanted empty, or it may be filled with growth factors, cells or fibers. The supply of NGCs is unlimited, and the tubes can be fabricated to optimum dimensions for nerve regeneration. Therefore, methods of producing suitable NGCs have been of great interest in recent years. NGCs have been produced from various biocompatible materials, such as collagen, PTFE, silicon, polyethylene, PLLA/CL, PGA, PLGA, and poly(phosphoester). Nerve guide conduits fabricated from biodegradable polymers are preferred over non-biodegradable polymers due to the obvious advantage of eliminating a second surgery to remove the NGC. Further, if a non-biodegradable tube is not removed after nerve regeneration, it leads to problems such as chronic tissue response or nerve compression.
Some known NGCs have a rigid structure. A drawback with these is that they may break after implantation. Other known NGCs are not particularly strong and may, for example, rip when being sutured in place or break after implantation. There is therefore a need for an improved NGC which may avoid some of the problems attendant with existing NGCs.